Rubber Ball response to impact?

Please forgive my ignorance on what may be simple topics for most of you. I'm just trying to get my head conceptually around a ball launching pet project I'm fiddling with.

If you take a rubber (tennis) ball, say of 5 oz mass, and blast it with a sprung plate moving at 70 mph, will the ball take off faster than 70 mph? Seems like it would due to the compression and rebound of the ball. How would you quantify that?

Along the same lines, which would yield a faster ball launch -- pushing it rapidly to 70 mph (so that it is somewhat compressed to plate during acceleration, or letting the plate get to 70 mph before it impales the stationary, possibly somewhat restrained, ball?

I believe it won't make much of a difference either way. In the first case however the ball will not travel faster, because the force needed to compress it, comes from the sprung plate. If anything it would receive lower kinetic energy than what comes from the plate because some the energy needed to compress it has turned into thermal energy in the ball.

Does the fact that the spring/plate assembly has much greater mass than the ball come into play. In other words, if you take the same amount of KE that exists in a massive spring/plate assy and transfer (a high %) of it to the ball, will the ball not react more "explosively?"